Self-diffusivities of N-2, CH4, and Kr on 4A zeolite pellets by isotope exchange technique

Citation
Dv. Cao et al., Self-diffusivities of N-2, CH4, and Kr on 4A zeolite pellets by isotope exchange technique, J PHYS CH B, 104(45), 2000, pp. 10498-10501
Citations number
12
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
15206106 → ACNP
Volume
104
Issue
45
Year of publication
2000
Pages
10498 - 10501
Database
ISI
SICI code
1520-6106(20001116)104:45<10498:SONCAK>2.0.ZU;2-V
Abstract
The isotope exchange technique (IET) was used to measure equilibria and kin etics for adsorption of pure N-2, CH4, and Kr on a 4A zeolite sample. The i ntracrystalline self-diffusivities for these gases were measured under trul y isothermal conditions. The self-diffusivities of Kr and CH4 were smaller than that of N-2 by 2 and 1 order of magnitude, respectively. The self-diff usivity of N-2 was independent of its surface coverage but the self-diffusi vities of CIC and Kr increased with increasing coverages in the high-pressu re region. This effect was much more pronounced for Kr. The activation ener gies for self-diffusion of the gases increased in the order Kr > CH4 > N-2 while the isosteric heats of adsorption of these gases in the Henry's law r egion were very close. The activation energies were larger than the corresp onding isosteric heats of adsorption for each gas.